The "eyes" (called "line guides") are generally made of stainless steel. It is what they are lined with that get's the fisherman's attention. Years ago, the best line guides were lined with agate,...
Rods are one of two types (the other are cones) of photoreceptor cells in the retina. Both are located at the back of the eye and gather strong and weak light. Rods are active at night and so are...